1. Field of the Invention
The present invention generally relates to an operation pattern selecting valve for enabling an operator to operate the tilt-type control levers on both sides of an operator's seat in an operation pattern conforming to the experience of the operator in view of the fact that in a working machine installed with a multi-joint front on an upper swing structure like a hydraulic excavator or an application machine thereof, which one of the tilt-type control levers is used to operate hydraulic cylinders for operating the multi-joint front and a hydraulic motor for a swing device in desired directions is different between manufactures or between a manufacture and the International Standard. More particularly, the present invention relates to a lock device for locking the operation pattern selecting valve so that the selected operation pattern cannot be changed by someone to enhance safety.
2. Description of the Related Art
Hydraulic excavators and various working machines constructed by applying their basic configurations thereto include a lower travel structure, an upper swing structure installed on the lower travel structure via a swing device, and a multi-joint front having a boom attached to the upper swing structure, an arm attached to the end of the boom, an operating tool such as a bucket attached to the end of the arm, and hydraulic cylinders for raising and lowering and swinging them. Tilt-type control levers for pilot valves for operating a hydraulic motor for swinging the swing device and for pilot valves for operating hydraulic cylinders of the multi-joint front are usually installed on the left and right sides in the front of the operator's seat as disclosed JP-U-5-47660 and JP-U-5-49858.
Each of such a control lever is operated forward, backward, leftward and rightward from a position where it is centrally raised, i.e., where the related actuators are stopped. For one manufacturer, forward and rearward operations of the right control lever correspond respectively to lowering and raising of the boom, and leftward and rightward operations of the right control lever correspond respectively to bucket-crowding (excavation) and bucket-dumping. Forward and rearward operations of the left control lever correspond respectively to rightward swing and leftward swing, and leftward and rightward operations correspond respectively to arm-raising and arm-lowering.
However, for a working machine of another manufacture, forward and rearward operations of the left control lever correspond respectively to arm-lowering and arm-raising and leftward and rightward operations correspond respectively to leftward-swing and rightward-swing.
As described above, the operation pattern of the control lever is different between manufactures or between a manufacturer and the International Standard. That is to say, which one of the left and right control levers is operated or which one of directions of forward and backward directions and leftward and rightward directions is selected by operating the control lever is different between manufactures or between a manufacturer and the International Standard. In such a case, if an operator who has been accustomed to operating a working machine of a manufacture operates another working machine of another manufacture, it becomes difficult for he or she to operate it and erroneous operation is likely to occur. For this reason, when a new working machine is used for operation, the operation pattern of a control lever is made to conform to an operation pattern to which an operator has been accustomed. In order to make the operation pattern selectable as described above, an operation pattern selecting valve is provided between pilot valves actuated by the control lever and the associated operating hydraulic fluid chambers of a control valve to switch hydraulic fluid passage.
The operation pattern selecting valve described in JP-U-5-47660 is configured such that an turn-type spool is fitted to the inside of a cylindrical body having ports connected to respective hydraulic lines. A shaft is secured to an end of this spool so as to project from a central hole of an end plate and a turn-type control lever is attached to the shaft so as to extend in a radial direction. Turning this control lever allows a port formed in the cylindrical body to communicate with another port and to be interrupted from the other ports.
If, after the turn-type control lever has been set to provide an operation pattern, this setting is changed by someone such as another operator, such an operation pattern selecting valve is likely to cause erroneous operation when operated by an operator who usually uses the operation pattern. To prevent such erroneous operation, JP-U-5-47660 and JP-U-5-49858 propose that the turn-type control lever is locked at a fixation position so that the operation pattern is not easily changed by someone.
The lock device described in JP-U-5-47660 is configured as below by way of example. A lock plate formed with a lock hole is attached to a bracket so as to be able to be raised and laid, the bracket being welded to a turn-type control lever. On the other hand, the head of a wing screw that secures the turn-type control lever to an end plate is formed with a lock hole. A lock is insertably attached to the lock holes of the lock plate and the wind screw for locking the turn-type control lever. In addition, another example is disclosed in which brackets formed with lock holes are attached to the turn-type control lever and a case and are locked by a lock for joint. In JP-U-5-49858, a turn-type control lever and a wing screw insertably attached to the control lever are formed with respective holes in a radial direction, into which a wire-type lock is inserted for attachment.